Pan Laboratory Research Interests
Gene therapy is generally defined as introducing a new gene (or DNA sequence) or a "repaired" version of an existing defective gene into a living human cell for therapeutic benefits. Since the first gene therapy clinical trial was initiated in 1991, this new therapy has evolved together with new developments in biotechnologies and better understanding of human diseases. There are currently over 600 gene therapy clinical trials worldwide for treatment of diseases such as cancers, genetics diseases and infectious diseases (http://217.215.32.12:80/trials/index.html). However, the wide application of this therapeutic approach is still awaiting improvements in the basic technology of gene transfer and cell targeting techniques, vector development, biology of targeted cells as well as in issues encountered when applying pre-clinical work to actual treatment for patients (translational research).
Dr. Dao Pan at Cincinnati Children's Hospital has long term research interests in combining translational and basic research on virus-mediated gene transfer and disease treatment for Mucopolysaccharidoses (MPS) disorders (especially MPS type I), which are often associated with systemic and central nerve system (CNS) abnormalities, and early childhood death (http://www.mpssociety.org/index.html). The current research focuses in the Pan laboratory include:
Optimization of retrovirus- or lentivirus-mediated ex vivo gene transfer and expression in hematopoietic stem cells (HSC)
Clinical efficacy has been achieved in certain clinical trials for children with X-linked severe combined immunodeficiency (X-SCID) using ex vivo HSC gene transfer. However, the general clinical application of this approach is still impeded by many difficulties such as low levels of HSC transduction, inadequate engraftment of transduced stem cells, and silencing of transgene expression. One of our attempts to overcome these problems involves the optimization of large-scale transduction protocols such as the pre-stimulation condition and the use of a bioreactor system. The potential application of in vivo selection is being evaluated in an MPS I knock-out mouse model by introducing a cancer drug-resistant gene (such as a variant 06-methylguanine DNA-methyltransferase [MGMT] or dihydrofolate reductase [DHFR]) in a bicistronic setting with the therapeutic alpha-L iduronidase (IDUA) gene. We are also evaluating the alteration of targeted cell subtypes and varied vector systems for therapeutic effects on the disease manifestations in MPS I mice.
Related Publications
Where possible, article titles are linked to an abstract of the article. Selected citations may also be linked to PDFs of the article available on a Journal's site. Depending on the Journal's publishing policy, you may need a subscription to download the PDF.
Pan, D., et al., Retroviral vector design studies toward hematopoietic stem cell gene therapy for mucopolysaccharidosis type I. Gene Ther, 2000. 7(21): p. 1875-83.
Pan, D., et al., "Supercharged Cells" for delivery of recombinant human iduronate-2-sulfatase. Mol Genet Metab, 2000. 70(3): p. 170-8.
Pan, D., et al., Combined ultrafiltration-transduction in a hollow-fiber bioreactor facilitates retrovirus-mediated gene transfer into peripheral blood lymphocytes from patients with mucopolysaccharidosis type II. Hum Gene Ther, 1999. 10(17): p. 2799-810.
Addressing the difficulties of transgene/vectors accessing the CNS
The problems of gene therapy for diseases involving the CNS are well known. In addition to the general difficulties of efficient gene transfer and effective and sustained transgene expression, there is the problem of transgene/vector access to the CNS due to the brain-blood-barrier. The application of lentivirus vectors, which were shown to be capable of transducing non-dividing cells such as brain neuronal cells, will be investigated using varied routes of in vivo administration. We will also study the potential usage of mesenchymal stem cells for treatment of CNS disease.
Evaluation of potential in vivo gene transfer into HSC and other organs
One goal of any clinical treatment is the correction of the target disease by a single injection of a therapeutic vector. Our previous studies have demonstrated successful pathological and neurological correction in MPS I mice following a single injection of a 3rd-generation therapeutic lentiviral vector at birth. This approach could potentially avoid difficulties encountered by ex vivo HSC-mediated gene transfer, such as stem cell differentiation during in vitro culture, loss of engraftment potential, toxicities related to HSC enrichment procedures and cytokine stimulation, and neutropenia related side effects. We are evaluating in vivo gene therapy in adult MPS I mice, comparing a systemic approach to a local injection. The "window of treatment" and in vivo pre-stimulation of cell proliferation will be explored with attempts to optimize gene transfer and transgene expression in liver, hematopoietic stem cells and the central nerve system. The potential application of in vivo gene therapy approach may open a door to a novel approach for disease treatment.
Related Publications
Where possible, article titles are linked to an abstract of the article. Selected citations may also be linked to PDFs of the article available on a Journal's site. Depending on the Journal's publishing policy, you may need a subscription to download the PDF.
Pan, D., et al., Metabolic and neuropathologic correction of Hurler syndrome by a single intravenous injection of lentiviral vector to newborn mice. Molecular Therapy, 2003. 7(5): p. s76.
Pan, D., et al., Biodistribution and toxicity studies of VSVG-pseudotyped lentiviral vector after intravenous administration in mice with the observation of in vivo transduction of bone marrow. Mol Ther, 2002. 6(1): p. 19-29.
For additional information, please contact Dr. Dao Pan Division of Experimental Hematology, at 513-636-6315. Dr. Pan's office can be found in room 6529 of Location R (Research Foundation Building).
